Switching system



Dec. 15, 1953 J. H. BRUNDAGE swrTcHING SYSTEM Filed Feb. l, 1952 IN V EL TOR.

JOHN H. BRUNDGE BY mh @06% TTORNE Y ff) (fr) (s Il' 2 jul' O "5 Patented Dec. 15, 1953 2,663,010 SWITCHING SYSTEM 1 I "'UtThis-*inventior--re1ates to -a Jnovel automatic electric fswitcliingfsystem' which is adapted to l aintainamredeterrninedoutput-signalandf particularly .tosuch fa-isystem*whichl may` be. assoia'tedwvith" a "carrierl telephone #systemf and which s';responsive to faulty'signal generationftherein.

iL.1`h,s,1sys tem isparticularlyadapted for operacin injc'onjun'clztion*with multi supply=sources;`

for examplejaprimarysource of suppl-yfand an ,auxiliary source of vSupply both having---identical A'operatingcliaracteristicsand each--coupledvto an loutput'. circuiti'` JI'thef'eIe'CtriCal energy,` -supplied from the 'primarysource deviates --from predetermined '.Iinflta theswitching; circuitf automatically uxiliarfy` sourCeJoIpllOYide"suitable `Eand continuust J*electric al energy to the? outputY thereof.

,object .'of,'the .,invention 'is to provide an f elet-rciswitchinearrangement having @1 -tripping :i:@circuiti.comiected inge;Vv .novel manner to-y auto,-

fanat'allv Switchthe' outplltfrqm a faulty-Supply -.sour,ce to. ari adequate substitute supply; source. c f-Anothenobiectoi myinyentionis to provide a novel;arrangement.- including am connection from etheoutput'of ,thesystem totheftripping device, A wherebtffthecdevce,.remains i11- its,.;tripped-posi iongactuating angalarm to indicate "ai faulty --,Siipp1y.source, l A Lfeatur'e Qfgrnyinvention is to:V provide a switching"arrangement 'whicheisfcontrollable to originally couple either of two sourcesofiisupply i. "to the/loutput'circuit.

" f hereisfprovided arfelectrical swlitchingfsystem ompri'singiprimaryandauxiliary zsourcesiof .elecf atrica'l f energ-yg ani ioutput'.V circuit:=.an'df.;me'ans-1` for nts-out Ethe;:plirriaify ,source'andl' cuts in ithe,

'j vInfaccordancei-"with one aspect "of'theinvention lalternatively couplingsthesourcesfof energyfgtoethe The ,i primary-source of f.

` John Hz-srundag'e;rCocoafFla.,fassjgnqrftohlnterational 1eleph0neion). ysucoli-poration of Maryland Applicationlehruary 1,?1'952; Serial No; 269,486

i 2 fJafi-lrstf control element ofthe Itrippable'ldevice to :;,......the first :elementfot the one; conductive device and to the second control element ofthe other' device. hfzlfMeansfare coupled togtheiirst element .of the 5 zother :device for: rendering. it. normally nonecon- .il ductive'.-l The trippable .device is` connectedtolthe 'z .routput whereby. a: portion. of. the` output. energy is l al'oplieclI thereto( :The biasingcircuit-isitadjusted :fort-biasing:the Vcnet-.device conductivevv andcithe 103 A other fdevicer lnon-conductive whiliel. thea. primary l 1 ysource'isolelivering a' normallsig'nal-fto: `rtheoutput Y circuitiV l-/Y-Uponn the ..primarysource delivering a faulty signal, `the trippable device V*is/tripped;and nroducesa-change -in the biasing circuit whereby 1'5- `Said` one device uis rendered#d non-conductiveand fthefsaidf' other device is rendered.- conductive V'and as aresult thereof, the output-circuit-lis switched from'the primary-source tol the `auxiliary source. 'lvieans` are provided for untripping -theltrippable 2U ldeviceV for' removing the change in. thebias' circuitV and-therefore Switehthe supply sources to j theirforiginaleonnections.

In-accordance-with amore speci-fic embodiment A of the invention, electron'tubesvare provided-'for ^the conductive devices Landia gas/discharge tube *is used forvthe-trippable device. 'The-1 above mentioned andi other Ifeatures-:and objects Yof '=this..'invention anditheay manner. of attaining 'them will.` becomer more; apparent-fand the invention- -itse1f-fwi11 be.;bestunderstood by reference tothe-following .description of an,y eml. bodiment of: Athe inventionl taken 'in'.Y conjunction withthe :accompanying drawingsw whereintthere ;.-1.: :is ;`i llustrated aschematic cliagramof an electronic .swtchngasystem .f -fleierrins .te theiigurehere is provided" an leflriqaliswitching system ,comprising primary and-auxiliary, sources of electrical energ having identicalelectrical.operating characteristics, coufioqpled via a switchingcircuit. to an output circuit.

fa-The Aswithirle Circuit wmp-rises@ pair 0f .electron-tubes. i' and f2,-r.espectively,Shaving their out- Y :.puts. connected ,parallel tok thefoutputl .circuit l,.ggovner., a,load resistor 3gTheuoutputlcircuits are connect@einriparato,.ma nuufntypezu tjwork, .whereby the Voutput froinleither source is, identical to .tlileipther .source when switching isl et'fected. Each of the electron tubes i,k.2..ln1ay bleoff'the 5yitriode-tynefhavieg an. anode, a rlirol far-id and a cathode. The primary andA auxiliarysources of g :electrical-energy are connected via condense'rs 4 5, jandfto.- the; controlggrids of celectrontubes.. V.and ,;2;1respective1 uegrid oetube Lis connected to a resistor 6'seriallyconnectedwith.acapacitor l to ground, and the grid of tube 2 is connected to a resistor ll serially connected with a capacitor 9 to ground. Tube i is self-biased by a cathode biasing circuit comprising a resistor Il? in parallel with a capacitor II; the parallel combination being connected at one end to ground. The bias for the cathode of tube 2 is provided by a B+ source of supply over a voltage divider network comprising resistors i2 and I 3 in series with a parallel circuit having a resistor I il in shunt with a capacitor I 5; the parallel circuit being connected to ground at one end.

A manually operable switch I6 controlling contacts Iba, Ib, Ic and Id is provided to connect the grid circuits of tubes i and 2 to ground and biasing circuit I8, II, respectively, and to connect the cathodes of tubes I and 2 to biasing circuits I, II and lll, I5, respectively, depending on whether the switch is positioned to connect the primary source to the output or the auxiliary source to the output. As shown in the drawing, the switch is positioned to connect the primary source to the output.

A tripping device in the form of a gas discharge tube Il, having a cathode, a control grid and an anode, is provided for sequentially or alternatively coupling the primary and auxiliary sources to the output. A portion of the output energy is coupled via line I8, rectifier i9, to a grid biasing circuit 26 consisting of a resistor 22 connected in parallel with a capacitor 23, and a resistor 2li coupled as a lpotentiometer to the control grid of the gas discharge tube. A resistor 2I is connected to the grid of tube I7. Since the output voltage is A.C., a rectier I9 is provided to rectify the energy applied to the grid biasing circuit of tube I'I. Capacitor 23 is thereby charged to a given voltage which voltage will drop if the output current fails. Resistor 22 and capacitor 23 provide a suitable time delay in the The anode of tube II is connected via resistor 28 to a relay 29 controlling switch 3i) which actuates an alarm system. The anode potential for tube Il is provided at 3l via reset switch 32.

Anode resistors 3S and 34 are provided in the plate circuit of tubes I and 2, respectively, to apply suitable potential to the anodes thereof.

Indicator circuits 35 and 36, each comprising a pair of resistors and a lamp, may be provided when it is desired to indicate the operation of the particular tube associated therewith. The indicator circuits 35 and 35 are connected across the outputs of tubes I and 2, respectively.

The operation of the system is hereinafter explained first, with the switch I6 in the position coupling the primary source with 'the output, and

' the adjustment of resistor 24.

secondly, in the position shown by the dotted l lines in the drawing, coupling the auxiliary source with the output.

The operation of the system with the switch positioned as shown is as follows:

Tube I is self-biased by resistor Il'I and a capacitor I I and normally conducts current. The grid return circuit is completed by contact Ia short-circuiting the capacitor "I,

The signal from the primary source is thus allowed to enter, is amplified in the usual manner and is applied through capacitor 3l to the output circuit. A portion of the output of tube I is routed to the grid circuit of the gas discharge tube Il, is rectified by the rectifier I9 and is applied across resistors 22 and 24 as grid bias for tube I'I. The amount of bias may be varied by As long as the signal from the primary source is of the proper level, the balance of voltages on the grid and on the cathode of tube I'I is such that the tube does not rire, and no current ows through it to relay 29 connected in its plate circuit, or in the cathode circuit thereof.

During the normal operation, tube 2 is nonconductive. By the voltage divider action of resistors I2, I3 and III, a fixed cut-off bias is provided from the B-I- supplied across resistor it. This bias voltage is Vpositive at the cathode of tube 2. At the same time, the voltage drop across resistor IIl in the cathode circuit of tube I is applied through resistor 8 to the grid of tube 2 as positive grid bias for that tube. The balance of voltages at the grid and at the cathode of tube 2 keeps this tube at cut-oil? during normal operation of the primary source. Since this tube is at cut-off, the signal from the auxiliary source is effectively blocked and cannot enter the output circuit.V

When the primary source fails or delivers a faulty signal, the voltage applied to the grid of tube I is greatly reduced. The portion of the signal voltage applied to the grid of tube I7 through rectier I9 is reduced accordingly and the balance of voltages applied to tube I'I is such that the tube fires. The resultant current ows through resistors I0, 25 and 26 and through the coil of relay 29. The increased voltage drop across resistor II) is positive at the cathode' of tube I, and is sufciently large to cut off this tube. The same voltage is applied through resistor 8 as aY positive voltage to the grid of tube 2. The voltage is high enough to overcome the cut-off bias across resistor It in the cathode of tube 2 and to cause this tube to conduct current. As a result of this action, the signal from the primary source is blocked from passing through tube I while the signal from the auxiliary source is allowed to go through tube 2 to the output circuit.

Relay 29 becomes energized by the current from tube ll flowing through it and moves contact 32 to actuate an alarm system which may consist of a lamp and buzzer system (not shown). When the trouble has been cleared, operation oi reset button 32 interrupts the current in the gas tube il. When this happens, the bias voltage distribution returns to the original condition, and provided the primary source is now providing a signal of the proper level, a signal voltage is applied to tube I. Tube I will continue to conduct current, while tube 2 is cut oif and blocks the signal from the auxiliary source. The circuit is thus restored to normal. It is to be noted that once tube I'I fires, it will continue firing and the portion of the energy fed back to its grid biasing circuit will have no elect on its operation. Therefore, the auxiliary source will remain coupled to the output until the faulty con-- dition of the primary is noted and reset switch 32 opened. l

With the switch I6 moved into the position shown by the 'dotted lines so that the auxiliary source is coupled to the output circuit, the `opera- Tube;l .isselibiasedfbyi resistir "10 to conduct plate-current. S-ignalsirom the auxiliaryrsource arepermitted to gofthru'gltube 2, are4 ampliiied inrthem'sual manner `land-'applied fthrcugh capacito' 38 to thebutputici'rcuit. Aaportion of the sig'nal"output'oftu`be 2is'outed through rectifier I9 where it is rectified and applied to tube I1 as cut-off bias, providing the signal level at the input to tube 2 is of the proper value.

At the same time tube I is kept at cut-01T by the voltage drop across the resistor network I0, 25 and 26. The bias voltage across resistor I0 which is now in the cathode circuit of tube 2 is also applied to the grid of tube I as a'positive voltage. The difference between the cathode and grid voltages of tube I, keeps this tube at cut-off and effectively blocks the primary source signal from passing therethrough.

When the signal voltage from the auxiliary falls below the required value, the cut-oi bias on the tube I1 is reduced sufficiently to cause the tube to iire. The plate current of tube I1 causes the relay 29 to become energized with the same results described in the rst mentioned case. Simultaneously, the cathode current of tube I1 flowing through cathode resistor I of tube Y2 drives this tube to cut-ofi and applies a suiiiciently high positive voltage to the grid of tube I to cause this tube to conduct. As a result, the signal from the auxiliary source is blocked, while the signal from the primary source is permitted to go through tube I to the output circuit. Thus the electronic switch changes the status from auxiliary source operation to primary source operation. Y

While I have described above the principles of my invention in connection with specific apparatus and circuitry, it is to be clearly understood that this description is made only by way of example and not as a limitation as set forth in the objects thereof 4and in the accompanying claims.

What is claimed is: Y

1. An electrical switching system comprising primary and auxiliary sources of electrical enorgy, an output circuit, and means for alternatively coupling said sources of energy to said output circuit whereby the primary source feeds the output circuit during normal operation of the system and the auxiliary source feeds the output circuit upon faulty operation of the primary source, said means comprising a pair of conductive devices having their outputs connected to the output circuit, each of said devices having at least two elements, the primary source of energy being connected to a first element of one of said devices and the auxiliary source being connected to a first element of the other conductive device, a trippable device controlling the sequence of operation of said conductive devices said trippable device having at least two elements, a biasing circuit coupled from a first element of said trippablc device to said first element of said one device and to the second element of said other device, means coupled to the first element of said other device rendering it normally non-conductive, a connection from said output to the second element of the trippable device whereby a portion of the output energy is applied thereto, the biasing circuit being adjusted for biasing said one device conductive and said other device non-conductive while the primary source is delivering a normal signal to said output cir- 6 ui admipon .saidaprimary source delivering a faultyfsignalgsaidltrippable devioeiibeing. tripped rrd-.1 producing :archange the-:biasing--ffcircuit whereby: said onefdeviceiisfirendered noneconducf .tive .andfsaidother d'evice. is* renderedrfccnductive and as a result thereof, the output-circuit is @switched .front the primarysourcetothe .auxiliary ource, 'and-'imeansf fon'untripping' fsaidtri'ppable f de'viceL-lwhereby:- thefchangefin -thefbias=fcircuit is ilcm'emoved .and theispplyisourceszare switched to their original connections.vv

i'2h-Theasysten'iraccording to claim 1, wherein said trippable device is a gas discharge tube.

3.The system according to claim 1, wherein said pair of conductive devices are a pair of electron discharge tubes.

4. An electrical switching system comprising primary and auxiliary sources of electrical energy, an output circuit, and means for alternatively coupling said sources of energy to said output, whereby the primary source feeds the output circuit during normal operation of the system. and the auxiliary source feeds the output circuit upon faulty operation of the primary source, said means comprising a pair of electron discharge tubes having outputs connected in parallel with the output circuit, each of said electron tubes having an anode, a control grid and a cathode, the primary source of energy being tubes and the auxiliary source being connected to the grid of the other electron tube, a gas discharge tube having an anode, a control grid and a cathode, a biasing circuit coupled from the cathode of the gas tube to the cathode of said one electron tube and to the grid of said other electron tube, a grid biasing circuit for said gas tube, means including a potential source coupled to the cathode of said other electron tube rendering it normally non-conductive, a connection from said output to said grid biasing circuit whereby a portion of the output energy is applied to the grid of said gas tube. the biasing circuits being adjusted for biasing said one electron tube conductive and said other electron tube non-conductive while the primary source is delivering a normal signal to said output circuit,

and upon said primary delivering a faulty signal to the output circuit, said grid biasing circuit being responsive hereto, to fire said gas tube thereby producing a change inthe biasing circuit coupled to the cathode of said one electron tube and the grid of said other electron tube, whereby said one electron tube is rendered non-conductive and said other electron tube is rendered conductive and as a result thereof, the output circuit is switched from the primary source to the auxiliary source, said auxiliary source supplying the electrical energy to said output circuit while said gas tube is conducting, and means for extinguishing said gas tube, whereby the change in the cathode bias circuit is removed and the supply sources are switched to their original connections.

5, The system according to claim 4 and further comprising an indicator circuit connected across each of said electron tubes, said indicator circuit comprising a lamp, whereby the operation of a particular electron tube is indicated by the lamp associated therewith.

6. The system according to claim 4, wherein said biasing circuit coupled from the cathode of the gas tube to the cathode of said one electron tube comprises a resistor in parallel with a capacitor.

connected to the grid of one of said electron 'i e '7. The system according to claim 4, wherein said grid biasing circuitrcomprses a resistor in Refelnes Clted 111 the le 0f thlS Patent parallel with a capacitor and a second resistor UNITED STATES PATENTS connected as a potentiometer to the'grid of said Number Y Name Date gsviglio whereby the bias of said gastube may 5 313,841 Wimsize et al. Man 10, 1885 8. The system according to claim 4, wherein J' 2 said outputs of the electron discharge tubes are e c g connected in a parallel nuil-T-type network so that the outputs from either of said sources are lo identical to each other.

JOHN H. BRUNDAGE. 

